fix: Use handler's __str__() in error messages.

Related: #

litestar/handlers/base.py

@@ -254,16 +254,6 @@ def handler_name(self) -> str:
         """
         return get_name(unwrap_partial(self.fn))
 
-    @property
-    def handler_fullname(self) -> str:
-        """Get the qualified name of the handler function.
-
-        Returns:
-            Qualified name of the handler function
-        """
-        handler_fn = unwrap_partial(self.fn)
-        return handler_fn.__module__ + "." + handler_fn.__qualname__
-
     @property
     def dependency_name_set(self) -> set[str]:
         """Set of all dependency names provided in the handler's ownership layers."""

litestar/handlers/http_handlers/base.py

@@ -574,7 +574,7 @@ def _validate_handler_function(self) -> None:
 
         if return_type.annotation is Empty:
             raise ImproperlyConfiguredException(
-                f"A return value of a route handler function {self.handler_fullname} should be type annotated. "
+                f"A return value of a route handler function {self} should be type annotated. "
                 "If your function doesn't return a value, annotate it as returning 'None'."
             )
 

litestar/handlers/http_handlers/decorators.py

@@ -597,7 +597,7 @@ def _validate_handler_function(self) -> None:
             or is_class_and_subclass(return_annotation, ASGIFileResponse)
         ):
             raise ImproperlyConfiguredException(
-                f"{self.handler_fullname}: Handlers for 'HEAD' requests must not return a value. Either return 'None' or a response type without a body."
+                f"{self}: Handlers for 'HEAD' requests must not return a value. Either return 'None' or a response type without a body."
             )
 
 

litestar/handlers/websocket_handlers/route_handler.py

@@ -85,25 +85,19 @@ def _validate_handler_function(self) -> None:
         super()._validate_handler_function()
 
         if not self.parsed_fn_signature.return_type.is_subclass_of(NoneType):
-            raise ImproperlyConfiguredException(
-                f"{self.handler_fullname}: WebSocket handlers must return 'None'"
-            )
+            raise ImproperlyConfiguredException(f"{self}: WebSocket handlers must return 'None'")
 
         if "socket" not in self.parsed_fn_signature.parameters:
-            raise ImproperlyConfiguredException(
-                f"{self.handler_fullname}: WebSocket handlers must define a 'socket' parameter"
-            )
+            raise ImproperlyConfiguredException(f"{self}: WebSocket handlers must define a 'socket' parameter")
 
         for param in ("request", "body", "data"):
             if param in self.parsed_fn_signature.parameters:
                 raise ImproperlyConfiguredException(
-                    f"{self.handler_fullname}: The {param} kwarg is not supported with websocket handlers"
+                    f"{self}: The {param} kwarg is not supported with websocket handlers"
                 )
 
         if not is_async_callable(self.fn):
-            raise ImproperlyConfiguredException(
-                f"{self.handler_fullname}: WebSocket handler functions must be asynchronous"
-            )
+            raise ImproperlyConfiguredException(f"{self}: WebSocket handler functions must be asynchronous")
 
 
 websocket = WebsocketRouteHandler